durability test results for the ssm 26-13 cookstove · 5 ssm 26-13 cookstove durability results...

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SSM 26-13 COOKSTOVE DURABILITY RESULTS

DURABILITY TEST RESULTS FOR THE SSM 26-13 COOKSTOVE

Prepared by:

Michael Johnson, Senior Scientist

Berkeley Air Front Range Testing Services

430 North College Avenue, Fort Collins, CO, USA

July, 2018

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Contents

Cookstove System Tested ........................................................................................................................ 3

Durability Test Protocol ........................................................................................................................... 3

Test Results ............................................................................................................................................. 6

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Cookstove System Tested Durability testing was conducted on the SSM 26-13 stove, manufactured by Zhejiang Huiwenmei Stove

Company, located at Dongxi Bridge, Ganlin Town, Shengzhou City, Zhejiang, China. The SSM 26-13 is a

side-feed, portable rocket-style stove with a metal combustion chamber, metal-clad body, and cast-iron

pot rest. The stove also has a metal fuel bed grate and a metal fuel rest grate that extends from the

combustion chamber. The primary fuel type for this stove is wood, which was used as the fuel for the

relevant burn tests in the durability protocol.

Durability Test Protocol

The stove was tested using the Cookstove Durability Test Protocol (v1.0), which assesses key

components of a stove’s design and materials with regard to potential failure. The test includes

assessments that stress a stove through extended burn times, external and internal physical impacts,

corrosion, coating adhesion, quenching, and material failure temperatures. These testing components

are briefly summarized below and the full protocol description can be found here:

http://cleancookstoves.org/binary-data/DOCUMENT/file/000/000/89-1.pdf. Importantly, the test is not

designed to provide an estimate of stove lifetime, which will be a function of the specific conditions it is

subjected to during real-world use, but rather provides an indication of which stove components are

likely to perform well or poorly over time.

1. Extended Burn

The stove is run at maximum firepower for four hours and is then allowed to cool completely. This

process is repeated three times. Changes in condition are then noted afterward and risk factor scores

assigned accordingly.

Level Examples Risk Factor No Change N/A +0

Minor Discoloration, minor abrasion, etc. +1

Major Cracks < 2 cm in length, twisted

metal, etc.

+3

Critical Broken components, cracks > 2 cm

in length, cloudy/hazy reflectors or

glass, etc.

+5

2. External Impact

The external surface of the stove is tested by dropping standardized weights from a 1m height onto the

surface of the stove. The drops are repeated sequentially from the heaviest to lightest weight until

damage is no longer visible.

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Lowest Weight at Which Damage is Seen

Risk Factor

No Damage Seen +0

250 g +1

200 g +2

150 g +3

100 g +4

50 g +5

25 g +6

3. Internal Impact

The internal impact test is conducted similarly to the external text but with the weights dropped onto

the internal stove surface. These are repeated sequentially from the heaviest to lightest weight until

damage is no longer visible.

Lowest Weight at Which Damage is Seen

Risk Factor

No Damage Seen +0

250 g +1

200 g +2

150 g +3

100 g +4

50 g +5

25 g +6

4. Corrosion

The corrosion test looks specifically at metal components of a stove. The metal components are

disassembled from the stove and heated to the temperature reached during the extended burn,

removed from the kiln, sprayed with a salt solution, and then left in a high humidity environment for 12

hours. This process is repeated for 10 cycles. The corrosion is measured in reference to a set of

reference metals that go through the same process for scoring purposes.

Material Rank Risk Factor Least Corrosion Seen +0

Second Place +0

Third Place +1

Fourth Place +3

Most Corrosion Seen +5

5. Coating Adhesion

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Coating adhesion is tested by heating the components with coatings to the temperatures achieved

during the extended burn test and then scoring a grid pattern onto them. Adhesive tape is then used to

determine how much coating is removed from the scored surface.

Coating Loss Risk Factor 0% +0

<5% +1

5%-15% +2

15%-35% +3

35%-65% +4

>65% +5

6. Quenching test

This test is designed to look at the impact of liquids overflowing from a cooking vessel onto the stove.

The stove is run at maximum firepower for one hour with a pot of water, after which additional water is

added to the pot so that it overflows a set amount. This sequence is repeated five times and then the

condition of the stove is then checked.

Level Examples Risk Factor No Change N/A +0

Minor Discoloration or cracks < 2 cm in

length.

+1

Major Warped components or cracks > 2

cm in length.

+3

Critical Broken or missing components,

cloudy or hazy reflectors or glass,

etc.

+5

Material Failure Temperature

This test is conducted by placing major stove components in a kiln and raising the temperature

sequentially at 50°C increments until the component fails (significant corrosion, loss of coating, melting,

twisting or warming, burning, scorching, and/or charring). The scoring is determined by using the

operating temperature during the extended burn test as a reference. Score (R) = extended burn temp /

failure temp.

R Risk Factor R<0.6 +0

0.6<R<0.7 +1

0.7<R<0.8 +2

0.8<R<0.9 +3

0.9<R<1 +4

R>1 +5

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Test Results The table below summarizes the overall durability performance of the SSM 26-13 stove. The overall

score for the stove was 4, with 1 risk factor point scored for only the extended burn, corrosion, coating

adhesion, and quenching tests. The overall score of 4 is at the highest Tier 5 performance level (<10) for

the ISO voluntary performance targets1. The extended burn test point arose from loss of a small amount

of paint on the external fuel rests. For corrosion, rusting was observed for the handle’s nuts and bolts

and external fuel rest. The external grate also lost some coating during the adhesion test, and there was

a small amount of discoloration on various parts of the stove following the quenching test. Specific

scores, photos, and notes can be found in the following datasheets.

Test component Stove Score

Possible score range (low score

being best) Extended Burn Test 1 0-5

External Impact 0 0-6

Internal Impact 0 0-6

Corrosion 1 0-5

Coating Adhesion 1 0-5

Quenching Test 1 0-5

Material Failure Temperature 0 0-5

Total 4 0-37

1 The ISO technical report on voluntary performance targets has been approved and publication is forthcoming.

DATA SHEET 1 EXTENDED BURN TEST

Cookstove Being Tested:______SSM Cook____ Test Dates________June 12 – July 17, 2018_______

Visual Inspection of Cookstove

Some small flecks of paint missing on underside of external coated grates on both stoves

Cookstove Schematic with Measurement Locations

Extended Burn Test Data Sheet 1 of 2 Date:__July 17th, 2018___________

Measurement Location Test 1 Test 2 Test 3

1 38.2 38.7 36.3 31.1 33.7 31.6 36.5 36.3 34.2

2 72.4 69.5 71.1 114.9 105.6 100.2 105.1 97.1 99.7

3 34.0 35.1 34.6 32.4 31.1 32.7 32.7 35.1 32.2

4 158.2 161.9 155.6 257.2 254.3 261.5 230.9 226.8 207.0

5 58.2 57.6 56.9 53.6 53.9 53.6 64.7 60.6 60.6

6 58.6 56.0 56.3 53.1 52.7 53.9 55.1 56.1 55.3

7 55.9 47.7 53.4 47.6 45.5 46.1 49.1 49.2 48.9

8 133.2 136.6 134.6 176.6 187.3 199.6 217.4 212.7 210.7

9 133.1 130.6 131.1 204.1 204.7 200.6 230.4 208.6 219.9

10 338.9 338.1 325.1 386.5 392.3 370.5 424.0 413.8 404.5

11 338.8 332.7 329.3 384.3 387.4 376.6 449.6 430.6 431.1

12 333.6 328.0 305.4 366.3 356.9 361.9 380.6 394.5 389.4

13 290.5 275.7 266.2 283.9 264.6 270.9 258.0 284.9 299.7

14 347.3 361.5 344.4 370.9 361.3 353.1 432.2 412.2 400.9

15 134.3 132.6 132.2 128.1 127.6 127.9 144.8 147.9 141.3

Notes: Temperatures in degrees Celsius

Risk Score

+1

Extended Burn Test Data Sheet 2 of 2 Date:__July 17th, 2018___________

DATA SHEET 2

EXTERNAL IMPACT TEST Cookstove Being Tested:______SSM Cook____ Test Dates________June 12 – July 17, 2018_______

Measurement Location Largest Mass at Which No Damage Is Seen

cast iron rim 250 grams

bottom of the stove 250 grams

side of the stove 250 grams

black coated chamber rim 250 grams

handle 250 grams

black coated external grate 250 grams

Risk Score

+0

Observations and Notes

• None of the parts sustained “substantial damage” as defined in the protocol • Bottom of the stove: there were small visible dents @ 250 g, 200 g, 150 g, 100 g, and 50

g; however, no dents were greater than or equal to 5 mm in depth (see photos) • Side of the stove: there were small visible dents @ 250 g, 200 g, 150 g, and 100 g;

however, no dents were greater than or equal to 5 mm in depth • Coated external grate: very small paint flecks at heaviest weight, barely visible (no lighter

weights tried) • All other components: no visible damage

External Impact Test Data Sheet 1 of 1 Date:__July 17th, 2018___________

DATA SHEET 3 INTERNAL IMPACT TEST


Measurement Location Largest Mass at Which No Damage Is Seen

ceramic plate 250 grams

internal metal structure 250 grams

internal non-coated grate 250 grams

Observations and Notes

• None of the parts sustained “substantial damage” as defined in the protocol • All components: no visible damage

Risk Score

+0 Internal Impact Test Data Sheet 1 of 1 Date:__July 17th, 2018___________

DATA SHEET 4 CORROSION TEST


Sample Material Temperature Target from Extended Burn Test Observations

handle 50 degrees Celsius Substantial rusting around nuts and bolts (+1)

bottom of the stove 150 degrees Celsius Some discoloration, no visible rust

side of the stove 150 degrees Celsius Some discoloration, no visible rust

black coated chamber rim 250 degrees Celsius Rust formed where coating peeled back

black coated external grate 250 degrees Celsius Fairly substantial rusting (+1)

internal metal wall 450 degrees Celsius Substantial discoloration, no visible rust

internal non-coated grate 450 degrees Celsius Substantial discoloration, no visible rust

Notes: No temperature obtained for internal and external grates due to issues measuring small points with laser thermocouple – maximum temperature of closest component used instead

Risk Score

+1

Corrosion Test Data Sheet 1 of 1 Date:__July 17th, 2018___________

CORROSION PHOTOS

DATA SHEET 5 COATING ADHESION TEST


Sample Material

Temperature Target from

Extended Burn Test

Observations Material Loss Estimation

black coated chamber rim 250 degrees Celsius Only a few small flecks of material removed <5%

black coated external grate 250 degrees Celsius Only a few small flecks of material removed <5%

Notes:

• No temperature obtained for internal and external grates due to issues measuring small points with laser thermocouple – maximum temperature of closest component used instead

• Unable to make full 20 cm slices on grate pieces

Risk Score

+1

Coating Adhesion Test Data Sheet 1 of 1 Date:__July 17th, 2018___________

ADHESION PHOTOS

DATA SHEET 6 QUENCHING TEST


Sample Material Observations

black coated external grate Some discoloration at the end nearest the fire

bottom of the stove Discoloration grew relative to end of the extended run test

internal metal wall Discoloration grew relative to end of the extended run test

internal non-coated grate Discoloration grew relative to end of the extended run test

Risk Score

+1

Quenching Test Data Sheet 1 of 1 Date:__July 17th, 2018___________

DATA SHEET 7 MATERIAL FAILURE TEMPERATURE TEST


Sample Material

Temperature Target from

Extended Burn Test

Observations Max

Temperature Tested

handle 50 degrees Celsius Cleared all levels 150 degrees Celsius

bottom of the stove 150 degrees Celsius Cleared all levels 250 degrees Celsius

side of the stove 150 degrees Celsius Cleared all levels 250 degrees Celsius

black coated chamber rim 250 degrees Celsius Cleared all levels, some coating pulled away at edges of the coupon

450 degrees Celsius

black coated external grate 250 degrees Celsius

Cleared all levels, exposed meal turned copper at 250 degrees Celsius. Likely prone to future failures but no

failure seen during testing

450 degrees Celsius

internal metal wall 450 degrees Celsius Cleared all levels, severe darkening of color but no failure

650 degrees Celsius

internal non-coated grate 450 degrees Celsius Cleared all levels, severe darkening of color but no failure

750 degrees Celsius

ceramic plate 430 degrees Celsius Cleared all levels 750 degrees Celsius

cast iron rim 230 degrees Celsius Cleared all levels 450 degrees Celsius

Notes: No temperature obtained for internal and external grates due to issues measuring small points with laser thermocouple – maximum temperature of closest component used instead

Risk Score

+0

Material Failure Test Data Sheet 1 of 1 Date:__July 17th, 2018___________

durability test results for the ssm 26-13 cookstove · 5 ssm 26-13 cookstove durability results...

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